Fire investigators are returning to the scene of two fires at schools in the Bay of Plenty

Firefighters were called to a fire at the playground at Rotorua's Malfroy School about five o'clock last night -- taking about an hour to extinguish it.

The blaze IS being treated as suspicious.

Three fire crews were also called to a single-storey fire at Tauranga's Bethlehem College about 7pm -- taking about three hours to fully extinguish it.

Fire and Emergency says that fire does NOT appear to be suspicious.